Overweight and obesity is a serious problem for Mexican-American children, due in part to poverty, acculturation, genetic predisposition or other factors. Clinic-based weight control studies have shown promise, but often include convenience samples with few or no Latino children. This randomized controlled trial will test the efficacy of a culturally and linguistically appropriate, evidence-based intervention to lower Body Mass Index (BMI) or slow weight gain among 390 overweight 6-9 year old Mexican-American children randomly sampled from a large (36,192 pediatric patients) community clinic providing services to low and medium income families in a US-Mexico border community (San Ysidro, CA). Intervention and measurement design and selection are based on a Socioecological Model for Latino Health Promotion. 69 Children and their parents will be randomly assigned to either a Special Intervention (SI) or Usual Care (UC) group. The SI group will participate in the following behavior change activities based on Prevention Plus and Structured Weight Management approaches 1 : (1) classes providing culturally-sensitive health education regarding healthy eating, increasing physical activity, decreasing sedentary behaviors, and effective parenting behaviors to model and reinforce children's health behaviors, instruction on how to modify both social and structural aspects of the home environment, and skills-building to navigate community resources; (2) group clinical visits (GCV) with a Health Educator and Mid-Level Provider (MLP); (3) family visits with primary care providers (PCP); (4) newsletters to refer families to community resources; and (5) phone calls to reinforce goal setting. The UC group will receive standard health education for childhood obesity already provided by the community clinic. The primary outcome for the study is child BMI, which along with other changes in physical outcomes, child health behaviors and parenting behaviors will be evaluated at four time-points (baseline, 6-, 12-, and 18-months). The primary hypothesis is that the SI group will demonstrate lower mean BMI than the UC group at the end of a 6 month intervention with a maximum difference occurring at 12 months, and will sustain this difference for an additional six months (18 months after baseline). Secondary aims include examining intervention effects on children's energy balance, physical activity levels, sedentary behavior and parenting strategies related to their children's health behaviors. This proposal is revised following a previous positive review. Changes in response to the review and other improvements include the addition of validity/reliability information for measures of electronic home devices, a complete dissemination plan, outcome data for preliminary studies, description of cohort retention strategies, clarification of intention to treat statistical modeling, inclusion of Structural Equation Modeling, increased effort level of co-investigators, consistent delineation of primary outcome (child BMI), sample teaching materials and description of teaching philosophy, estimates of clinic visit revenues, and procedures to reduce potential participant coercion to enroll in the study. PUBLIC HEALTH RELEVANCE: Overweight and obesity is arguably the single biggest health threat to America's children, and is a special problem for Mexican-American and other Latino youth due in part to poverty, acculturation, genetic predisposition and other factors. Clinic-based weight control studies have shown promise, but often include convenience samples with few or no Latino children. This randomized controlled trial will test the efficacy of a culturally and linguistically appropriate, evidence-based intervention to slow weight gain or promote weight loss among Mexican-American children randomly sampled from a large community clinic providing services to low and medium income families in a US-Mexico border community (San Ysidro, CA).